The referenced German published Patent Application DE-AS No. 20 26 355 describes a turning rod, particularly adapted to change the direction of paper webs in which the paper web is passed around the turning rod, while the turning rod is washed with air flow. To provide for the air flow, the turning rod is formed with air exit openings, and constructed in form of a hollow tube, supplied with compressed air from a compressed air source. Consequently, the paper web which is passed around the turning rod can be floated thereabout, and thus abrasive contact with the truning rod or bar is prevented. The referenced German application describes cover sheets to cover selected air exit openings on the turning rod.
It has been found that placing cover openings, or tube sections about a turning rod causes damage to the material which is to be turned, or wrapped thereabout, and such elements are particularly undesirable if the web being turned or passed over the turning rod is paper. Contact with a turning rod cannot be prevented and the web is subject to damage particularly if the turning rod should not be perfectly aligned with respect to the web, or improperly adjusted. Personal judgement of operators, thus, is frequently required to permit operation of such a turning rod without difficulty. Individual coverage of any one of the air exit openings which may not be needed is not possible by this system; only air exit openings located at end or edge portions can be effectively controlled.